Inadequate rates are lower when FNAC samples are taken by cytopathologists

Inadequate rates (IR) in FNAC from different sources were compared. The rates were lowest when FNAC was performed by a cytopathologist (12%) and highest when done by a non-cytopathologist (32%). These differences were mirrored in high IRs in breast cancer cases. IR was not significantly improved when non-cytopathologist FNAC was attended by a cytotechnician.     

Kinetic parameters of Zn uptake by wheat are affected by the herbicide chlorsulfuron

Kinetic parameters of Zn uptake were determined for wheat plants(Triticum aestivum cvs Excalibur and Gatcher, and Triticum turgidumconv. durum cv. Durati) pre-grown at deficient or sufficientZn supply and with 0 or 4 mg m^-3 sulphonylurea herbicide chlorsulfuron(2-chloro-N-(((4-methoxy-6-methyl-1,3,5-triazin-2-yl) amino)carbonyl)-benzenesulphonamide].Net Zn uptake generally showed a saturable response to increasingsolution Zn concentrations; this response fitted a modifiedMichaelis-Menten equation incorporating the C_min term (solutionconcentration when net uptake is     

Chloroplasts are partially mobilized to the vacuole by autophagy

Excluding the central vacuole, chloroplasts constitute the largest compartment within the leaf cells of plants and contain approximately 80 percent of the total leaf nitrogen, mainly as proteins. Much of this nitrogen is allocated to the carbon-fixing enzyme in photosynthesis, Rubisco. During senescence, plants can mobilize nitrogen from chloroplasts in older leaves to other organs, such as developing seeds. Whereas bulk degradation of the cytosol and organelles in plants occurs by autophagy, the role of autophagy in the degradation of chloroplast proteins is still unclear. We have recently demonstrated that stroma-targeted green fluorescent protein (GFP), DsRed, and GFP-labeled Rubisco can be mobilized to the vacuole of living cells via Rubisco-containing bodies, in an ATG gene-dependent manner. Our results indicate the presence of a specific autophagic pathway for chloroplast stromal proteins, which does not cause chloroplast lysis. Here, we also discuss the involvement of stroma-filled tubules, stromules, which are important for the structural flexibility of the organelle, on the autophagic transfer of stromal proteins to the vacuole.     

How are substrates recognized by the ubiquitin-mediated proteolytic system

A necessary step in the degradation of proteins by the ubiquitin system is recognition by the ubiquitin-protein ligases(s). Various structural features of the proteolytic substrate render it susceptible to conjugation with ubiquitin. The N-terminal residue plays a major role in this process, with distinct sites on the ligase(s) recognizing specific types of N-termini. Post-translational modification of some of these residues is required prior to their recognition. A free N terminus is not the only marker; proteins with either free or blocked N termini can be recognized via structural domains that are downstream and distinct from this residue.     

Inactivated sodium channels are blocked by the anti-arrhythmic cordaron

The blocking action of the antiarrhythmic cordaron (amiodaron hydrochloride) on Na currents in the frog node of Ranvier was studied by the voltage-clamp technique. It was established that the degree of the cordaron-induced block can be reversibly increased by long-term (1 s and more) membrane depolarization. The time constants of both the development and recovery from the block caused by membrane depolarization are of the order of hundreds of seconds ("induced slow sodium inactivation"). The fraction of blocked channels rises to some limiting level with an increase in the magnitude of the depolarizing step, the region of strong voltage dependency being between -130 and -70 mv. The inhibition of outward potassium current by 7.10(-4) M cordaron does not exceed 15%. The time- and voltage-dependent block of Na channels is supposed to result from interaction of the antiarrhythmic with inactivated channels.     

Effects by doxorubicin on the myocardium are mediated by oxygen free radicals

We hypothesized that doxorubicin (DOX) induces cardiotoxicity of myocardium via oxygen radicals. The present study is aimed at examining the membrane alterations by oxygen radicals generated by DOX in adult rats and cultured neonatal myocytes. Our results showed that DOX 1) decreased beta-adrenoceptor (BAR) density in the cell membrane, 2) increased the membrane permeability of cultured neonatal rat myocytes and 3) altered the ultrastructure of myofibrils and subplasmalemmal actin networks. These effects were reproducible by exogenous hydrogen peroxide. The antioxidant melatonin (MLT) inhibited enzyme leakage and peroxidation in a concentration-dependent manner. It is concluded that DOX induces cardiotoxicity through lipid peroxidation and melatonin is an effective antioxidant against the reactive oxygen intermediates generated by DOX.     

Sleep changes induced by lipopolysaccharide in the rat are influenced by age

In mammals, aging is associated with immune senescense. To examine whether the sleep changes occurring during immune challenge are affected by age, we assessed sleep alterations induced by the administration of lipopolysaccharide (LPS) in young and middle-aged rats. During vehicle, the middle-aged rats exhibited less pre-rapid eye movement sleep (pre-REMS) as well as REMS, due to a smaller number and shorter duration of REMS episodes, than young rats. LPS elevated body temperature, increased non-REMS, and suppressed both pre-REMS and REMS in the young as well as in the middle-aged rats. However, in the young animals, LPS significantly enhanced slow-wave activity in the electroencephalogram (EEG) within non-REMS, reflecting an increase in sleep intensity. In contrast, LPS attenuated EEG power in most frequency bands in the older animals. This finding indicates age-related changes in the modulation of sleep by LPS.     

Modified dsRNAs that are not processed by Dicer maintain potency and are incorporated into the RISC

Chemical modification of RNA duplexes can provide practical advantages for RNA interference (RNAi) triggering molecules including increased stability, safety and specificity. The impact of nucleotide modifications on Dicer processing, RISC loading and RNAi-mediated mRNA cleavage was investigated with duplexes ≥25 bp in length. It is known that dsRNAs ≥25 bp are processed by Dicer to create classic 19-bp siRNAs with 3′-end overhangs. We demonstrate that the presence of minimal modification configurations on longer RNA duplexes can block Dicer processing and result in the loading of the full-length guide strand into RISC with resultant mRNA cleavage at a defined site. These longer, modified duplexes can be highly potent gene silencers, with EC50s in the picomolar concentration range, demonstrating that Dicer processing is not required for incorporation into RISC or potent target silencing.     

Esr proteins are secreted by the cells of the embryo surrounding region

Three highly homologous Esr genes are expressed specifically in the embryo surrounding region at the micropylar end of the maize endosperm. The proteins belong to a family of small hydrophilic proteins that share a conserved motive with Clv3, the ligand of the receptor-like kinase Clv1. In this study, co-localization of Esr proteins with their mRNAs in the embryo surrounding region was shown with polyclonal antibodies recognizing all three Esr proteins. On a subcellular level the secretion of Esr proteins and their association with the cell wall was shown independently by cell fractionation, immunohistochemistry and transient expression of Gfp fusion proteins. Furthermore, a possible interaction of Esr proteins with a 35 kDa protein present in the lower half of maize kernels was suggested by in vitro affinity chromatography. Therefore Esr proteins share two characteristics with ligands of receptor-like kinases: they are released in the extracellular space and they have the capacity to form protein-protein interactions.     

HPLC conditions are critical for the detection of GABA by microdialysis

In microdialysis studies, neither exocytotic release of gamma-aminobutyric acid (GABA), nor the presence of GABA type B (GABA(B)) autoreceptors, have been clearly established. It was investigated whether the chromatographic separation of GABA may have contributed to discrepancies in the literature. After extending the profile of the HPLC chromatogram to a retention time of 60 min, it was observed that various unknown compounds of biological origin co-eluted near the GABA peak. The retention time of GABA appeared to be extremely sensitive to pH; even at a retention time of around 60 min there was only a small pH window (5.26 +/- 0.01) where GABA was consistently well separated from co-eluting compounds. GABA determined by the improved assay was sensitive to tetrodotoxin (TTX), calcium depletion and the GABA(B) autoreceptor agonist baclofen. The present results illustrate that if the proper analytical conditions are applied, extracellular GABA can be sampled and quantified by microdialysis in free-moving animals. However, when the time-curves are considered, there is a striking delay of about 15-30 min before the effects of TTX, calcium depletion or baclofen are observed, as compared to the reported response of neurotransmitters such as dopamine (less than 5 min). It is assumed that the glial cells serve as a buffer between the GABA synapse and the microdialysis probes. It is proposed that microdialysis samples measure synaptic GABA indirectly, through glial cells surrounding the synapses.     

Protein-heparin interactions measured by BIAcore 2000 are affected by the method of heparin immobilization

Surface plasmon resonance (SPR) biosensors such as the BIAcore 2000 are a useful tool for the analysis of protein-heparin interactions. Generally, biotinylated heparin is captured on a streptavidin-coated surface to create heparinized surfaces for subsequent binding analyses. In this study we investigated three commonly used techniques for the biotinylation of heparin, namely coupling through either carboxylate groups or unsubstituted amines along the heparin chain, or through the reducing terminus of the heparin chain. Biotinylated heparin derivatives were immobilized on streptavidin sensor chips and several heparin-binding proteins were examined. Of the surfaces investigated, heparin attached through the reducing terminus had the highest binding capacity, and in some cases had a higher affinity for the proteins tested. Heparin immobilized via intrachain bare amines had intermediate binding capacity and affinity, and heparin immobilized through the carboxylate groups of uronic acids had the lowest capacity for the proteins tested. These results suggest that immobilizing heparin to a surface via intrachain modifications of the heparin molecule can affect the binding of particular heparin-binding proteins.     

Ghrelin receptors are expressed by distal tubules of the mouse kidney

Ghrelin, a peptide hormone from the stomach, has been recently discovered to reduce sodium excretion from the kidney. Although the effects on the kidney suggest actions in the distal nephron, the sites of expression of ghrelin receptors have not been localised. In the present work we have used a mouse that expresses green fluorescent protein under the control of the ghrelin receptor promoter to locate sites of receptor expression in the kidney. Receptor expression was confined to the straight parts of the distal tubules and the thin limbs of the loops of Henle. No expression was detected in other structures, including the glomeruli, proximal tubules and collecting ducts. Ghrelin receptors were not found in extra-renal or intra-renal arteries, despite observations that ghrelin is a vasodilator. The distribution revealed by in situ hybridisation histochemistry was the same as that revealed by the reporter. In conclusion, ghrelin receptors have a restricted distribution in the kidney. The location in the straight parts of the distal tubules accords with observations that ghrelin promotes sodium retention.     

Gas vesicles are strengthened by the outer-surface protein,GvpC

The critical collapse pressure of gas vesicles isolated from Anabaena flos-aquae decreased from 0.557 to 0.190 MPa when GvpC, the hydrophilic 22 kDa protein present on the outer surface of the gas vesicle, was removed by rising in 6 M urea. Recombinant GvpC was purified from inclusion bodies, produced in an E. coli strain containing an expression vector bearing the gene ecoding GvpC from A. flos-aquae, and then solubilised in 6 M urea. This recombinant GvpC became bound to gas vesicles that had been stripped of their native protein, when the urea was removed by dialysis; the amount which bound increased with the concentration of GvpC present. The critical pressure of these reconstituted gas vesicles increased to 0.533 MPa, 96% of the original value. These results indicate that the function of GvpC is to increase the strength of the structure.Non-standard abbreviations SBTI Soy bean trypsin inhibitor - Gvp Gas vesicle protein - SDS Sodium dodecyl sulphate - PAGE Polyacrylamide gel electrophoresis     

Eucalypt seedlings are aided by phosphorus in the face of drought

Drought is an increasingly common climatic event that can devastate ecosystems, as well as surrounding agricultural and forestry industries. Few places face this challenge more than Australia, where millennia of droughts linked to geography and climatic drivers, such as El Niño, have shaped the flora and fauna into forms predicated on resilience and economy. How an organism responds to these cyclic challenges is a combination of the inherent tolerance mechanisms encoded in their genome and outside influences, such as the effect of nutrients and symbiotic interactions. In this issue of Physiologia Plantarum, Tariq et al. (2019) describes how the presence of the element phosphorus can bolster the physiological and biochemical response of eucalypt seedlings to severe drought conditions.     

The metabolic effects of oxytocin are mediated by a uterine type of receptor and are inhibited by oxytocin antagonist and by arginine vasopressin in the dog.

Infusion of oxytocin (OT) into normal dogs, in doses which produced plasma levels of OT in the physiological range, has been shown to increase plasma levels of glucose, insulin and glucagon and increase rates of glucose production and uptake. This study sought to determine whether there was a correlation between these metabolic effects and the oxytocic potency of four less potent oxytocic analogues when infused into normal dogs. The rank order of oxytocic potency of all 4 correlated well with the rise in plasma glucose levels, and in 3 of the 4 with the rise in plasma insulin levels. An antagonist of the oxytocic effect of OT suppressed the usual OT-induced rise in plasma glucose, insulin and glucagon as well as the increased glucose production and uptake. Arginine vasopressin (AVP) infusion, which by itself did not produce any metabolic effects, blocked completely the effects of OT infusion to raise plasma glucose and insulin levels and increase glucose production and uptake. The data suggest that the metabolic effects of OT in the dog are mediated by OT receptors that are similar to those producing the oxytocic effects. Whether the inhibition by AVP of the metabolic and hormonal effects of OT occurs at the receptor or post receptor level or via other mechanisms remains to be determined.     

Phycoerythrins of the oxyphotobacterium Prochlorococcus marinus are associated to the thylakoid membrane and are encoded by a single large gene cluster

An intrinsic divinyl-chlorophyll a/b antenna and a particular form of phycobiliprotein, phycoerythrin (PE) III, coexist in the marine oxyphotobacterium Prochlorococcus marinus CCMP 1375. The genomic region including the cpeB/A operon of P. marinus was analysed. It encompasses 10153 nucleotides that encode three structural phycobiliproteins and at least three (possibly five) different polypeptides analogous to cyanobacterial or red algal proteins involved either in the linkage of subunits or the synthesis and attachment of chromophoric groups. This gene cluster is part of the chromosome and is located within a distance of less than 110 kb from a previously characterized region containing the genes aspA-psbA-aroC. Whereas the Prochlorococcus phycobiliproteins are characterized by distinct deletions and amino acid replacements with regard to analogous proteins from other organisms, the gene arrangement resembles the organization of phycobiliprotein genes in some other cyanobacteria, in particular marine Synechococcus strains. The expression of two of the Prochlorococcus polypeptides as recombinant proteins in Escherichia coli allowed the production of individual homologous antisera to the Prochlorococcus and PE subunits. Experiments using these sera show that the Prochlorococcus PEs are specifically associated to the thylakoid membrane and that the protein level does not significantly vary as a function of light irradiance or growth phase.